No , what I want is to show one of the lines crossing over the other one. I've seen it in drawings represented by one of the lines having a U shape over the other one. I thought this would be a very common tool.

- draw circle for example with radius 2 at crossing
- use the "break out segment" tool to delete the two segments you don't want (inside the circle)
- Delete half of circle, leaving something that looks like one wire jumped over the other one.

Alternately (and easier I think):

adopt the convention that crossing lines do not intersect unless there is a dot or small circle on the intersection. Then, you only need to paste a dot at each intersection, which is only 1 step.